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• FFMPEG and JNI - pass AVFrame data to Java and Back

  17 octobre 2015, par tishu

  I have some C code that decodes a video frame by frame. I get to a point where i have an AVFrame in BGR32 and would like to send it back to Java for editing.

  I have a ByteBuffer object in my C code that was created in Java using AllocateDirect but i struggle to write the content of the AVFrame->data[0] (of uint8_t type) to it and read it back. I have tried memcpy with no luck. Does anyone have an idea how to achieve this ?

  UPDATE
  Followed Will’s comment below and wrote this in C

  char *buf = (*pEnv)->GetDirectBufferAddress(pEnv, byteBuffer);
  
  memcpy(buf, rgb_frame->data[0], output_width*output_height*4);

  The buffer does contain some data in Java but doing the following returns a null bitmap

  BufferedImage frame = ImageIO.read(bitmapStream);

  Where bitmapStream is a ByteBufferInputStream defined here :
  https://code.google.com/p/kryo/source/browse/trunk/src/com/esotericsoftware/kryo/io/ByteBufferInputStream.java?r=205

  Not sure if I am not writing things correctly in this buffer

  UPDATE 2

  Got pretty close now thanks to the latest snippet. I am using BGR32 format in my C code ie 4 bytes per pixel. So I modified things a bit in Java :

  final byte[] dataArray = new byte[width*height*4];
  
  imageData.get(dataArray);
  
  final BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);
  
  final DataBuffer buffer = new DataBufferByte(dataArray, dataArray.length);
  
  Raster raster = Raster.createRaster(sampleModel, buffer, null);
  
  image.setData(raster);

  I get the image correctly but there seems to be an issue with color channels
  

  Tried different formats with no luck

• delay in lyrics shown when concat video with lyrics with an intro video using ffmpeg

  19 mars 2018, par no name

  I have a video with lyrics I add the lyrics used ffmpeg too. I have the lyrics in lrc formate and i change it to ass lyrics formate then I start to add it to my video using this command

  ffmpeg -i video.mp4 -vf "ass=out.ass,fade=in:0:30" -y amr.mp4

  I use fade=in:0:30 to make fade in the start of the video so when I start merge intro video my original video not start at once but to have some fade in, in the start to have a good view.
  then I start to add the intro video using a text file which has this

  file intro.mp4
  
  file amr.mp4

  then I merge them using this command

  ffmpeg -f concat -safe 0 -i out.txt -c copy -y final.mp4

  i got these message

  [mov,mp4,m4a,3gp,3g2,mj2 @ 03eadb80] Auto-inserting h264_mp4toannexb bitstream filter
  
  [mp4 @ 06419580] Non-monotonous DTS in output stream 0:1; previous: 310272,     current: 285626; changing to 310273. This may result in incorrect timestamps in   the output file.

  repeated many times.
  when i watch the final video the lyrics have some delay from the sound the problem appeared when I merge the intro video but without it the lyrics have no problem so what I made wrong make the lyrics shown in this way and not in the right timing as it should have no problems as I merge only the intro video and after add the lyrics to the original one
  Thanks in advance

• configure : fix linking with MSVC when using —disable-optimizations

  15 décembre 2016, par Steve Lhomme

  configure : fix linking with MSVC when using —disable-optimizations
  Without any optimization flags, MSVC does no dead code elimination (DCE) at
  
  all, even for the most trivial cases. DCE is a prerequisite for building libav
  
  correctly, otherwise there are undefined references to functions for other
  
  architectures and disabled components.
   O1 is the minimal optimization flag for MSVC that does include DCE.
  

  • [DBH] configure